This application claims the benefit of Korean Application No. 2001-5938, filed Feb. 7, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a functional film, and more particularly, to a functional film having adjustable optical and electrical properties and a method of manufacturing the same.
2. Description of the Related Art
A functional film having electrical conductivity while minimizing reflectance of external light has a variety of applications. These applications include use in sun glasses, external light shielding glass, UV protective and insulating materials, and electromagnetic shielding materials. The functional film can also be used as a black matrix formed between phosphor layers of a color display device, such as a color cathode ray tube. In this content, the functional film absorbs both external light and light scattered from adjacent phosphor layer patterns.
Generally, as the reflectance of the external light of a screen of a display device increases, a visible image becomes increasingly blurred. Since the external light is reflected mainly at a black matrix of the screen, attempts to improve the luminance and the contrast by increasing the absorbance of the black matrix surrounding pixels of the display device have been continuously made. Thus, a black matrix is fabricated to have a laminated film structure using chromium, and more specifically, a film structure consisting of a chromium layer and a chromium oxide layer. In order to further increase the absorptivity of the black matrix, carbon is added to the chromium oxide layer.
U.S. Pat. No. 5,976,639 discloses a method of forming a black matrix for a liquid crystal display using a laminated film consisting of a transition layer and a metal layer on the inner surface of a display panel. According to this patent, the laminated film has a transition layer in which the content of one constituent element, such as Cr, W, Ta, Ti, Fe, Ni or Mo, increases approximately between 0.5% and 20% per 100 xc3x85 in the incident direction of external light. The transition layer may further include a constituent element such as oxygen (O), nitrogen (N) or carbon (C). The constituent element of the transition layer is desirably chromium. The transition layer is disposed between a low metal layer and a high metal layer. The content of metal elements of the high metal layer is in the range of 50 to 100% by weight, and the content of metal elements of the low metal layer is in the range of 10 to 50% by weight.
However, the black matrix described in U.S. Pat. No. 5,976,639 uses materials that are environmentally detrimental, such as chromium. Also, a highly efficient functional film whose refractive index and electrical conductivity can be adjusted is not disclosed therein.
To solve the above and other problems, it is an object of the present invention to provide a functional film having good mechanical, optical and electrical properties by using a mixture of nontoxic metal other than chromium and a dielectric material.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To accomplish the above and other objects, a functional film according to an embodiment of the invention includes a transition layer including a first constituent selected from a group consisting of from aluminum (Al) and silicon (Si) and a second constituent selected from a group consisting of oxygen and nitrogen, the first and second constituents having corresponding gradual content gradients that vary according to a thickness of the functional film.
According to an aspect of the present invention, the gradual content gradients are distributed such that a refractive index of the functional film gradually increases or decreases in an incident direction of external light according to the thickness of the functional film.
According to another aspect of the present invention, the gradual content gradients are distributed such that a light absorption efficiency gradually increases in the incident direction of the external light according to the thickness of the functional film.
According to a further aspect of the present invention, the first constituent is aluminum and the gradual content gradients are distributed such that an electrical conductivity gradually increases or decreases according to the thickness of the functional film.
According to yet another aspect of the present invention, the gradual content gradients are distributed such that a content of the first constituent gradually increases and a content of the second constituent gradually decreases in the incident direction of the external light according to the thickness of the functional film.
According to still another aspect of the present invention, the functional film is deposited on a substrate, where a difference in a refractive index at an intersection of the substrate and the functional film is less than or equal to 0.5.
According to another embodiment of the present invention, the functional film further includes a conductive layer consisting of at least one metal constituent selected from the group consisting of titanium (Ti), aluminum (Al), silver (Ag), copper (Cu), gold (Au), platinum (Pt), cobalt (Co), iron (Fe) and indium tin oxide (ITO), and the first constituent forming the functional film having the conductive layer is Si or Al.
According to a yet still further aspect of the present invention, the conductive layer is formed on a face opposite the intersection between the functional film and the substrate when the functional film is used in the fields requesting electrical conductivity characteristics, the first constituent is silicon, and the Si content increases according to the thickness of the functional film.
According to a further embodiment of the present invention, the functional film is used as a black matrix in a display device.
According to a yet further embodiment of the present invention, the functional film further includes a conductive layer used as electrodes of a display device.